Automatic air cut-off for burners



March 15, 1938. c, w Ds f 2,111,484

AUTOMATIC AIR CUT-OFF FOR BURNERS Filed Aug. 19, 1956' I i 1.1 H l 15 It is an object of my invention to provide coaxlally with the nozzle H, the wall ll thereof 15 40 complete understanding of the invention. In plate 3. Air for combustion may then be in- 40 5o tor l projects a short' distance into the heat'ex the bellows 24 and 25 and cause the edge of the so Patented Mar. 15,1938 4 UNITED STATES PATENT OFFICE AUTOMATIC AIR CUT-OFF FOR BURNERS James O. Woodson, Cleveland, Ohio, assignor to Lee Wilson, Cleveland, Ohio Application August 19, 1936, Serial No. 96,806

2 Claims. (Cl. 158119) This invention relates to a fuel burner and, in which a threaded sleeve 6 extends, being secured particular, a to a device for. automatically conthereto by bolts I extending through ears 8 trolling theamount of air supplied to support formed on the sleeve. A fuel-supply connection combustion. 9 is threaded into the outer end of the sleeve 6.

5 Radiant tubes heated by combustion gases A nipple I is threaded into the inner end of the passing therethrough have proved highly successg sleeve 6 and carries a nozzle ll being connected ful for general heating'applications, such as the thereto by a coupling l2. The nozzle II has a annealing furnace described and claimed in tip l3 with a'central bore M which is adapted United States patent to WilsonNo. 1,952;402. It to deliver a jet of fuel into the throat of the in- 10 has been found, however, that when such appaspirator tube I when fuel under pressure is de- 10 ratus is operated at a relatively low rate, the inliv-ered to the connection 9. duction of air through the radiant tubes caused A cup I! having a cylindrical side wall l6 and by natural draft abstracts an excessive amount of a rear'wall I1 is adapted to engage the flange heat and prevents emcient operation. P e 3 w its edgee D is disposed means for preventing the induction of excessive having an opening 18 through which the nozzle amounts of cold air through radiant heating extends. The edge of the cup I5 is normally tubes, and the resulting loss of heat. In accordurged against the plate 3 by a compression spring ance with my invention, I provide a movable l9 disposed between a washer 20 backed up by a 20 valve or closure member for restricting the innut 21 threaded on the nipple l0 and the rear wall 20 flow of air to the burner when operating under I! of the cup l5. A collar 22 extending around low fuel pressures. The closure member may the-opening ill in the rear wall I! of the cup l5 conveniently take the form of a cup adapted to provides a seat for the springlll. abut, with its edge a flange plate extending from A plate or disc 23 is secured on the nozzle ll',

the inspirator tube usually incorporated in fuel having a hole through which the nozzle extends. 25 burners to induce air for combustion thereinto. Coaxial bellows 24 and 25 are secured at oppo- Fuel is supplied to the inspirator by a nozzle, and site ends to the plate 23 and the wall I! of the I mount the cup or closure on the nozzle for cup 15. These bellows define an annular ex- 'movement relative thereto. An expansible champansible chamber. The nozzle II has a port 26 30 her subject to the pressure of the fuel in the in alinement with aradial passage 21 in the plate 30 nozzle serves to move the cup to the position in 23. An axial passage 28 in the latter interwhioh it permits free induction of air, when the Sec/Bing the radial P e dm ts uel from the fuel pressure is at a maximum. At lower fuel nozzle H to the annular chamber defined by the pressures, the cup moves to partially or completebellows.

1y closed position under the influence of a closing It will be apparent. from the foregoing de- 5 spring. I I scription that when the fuel supplied to the nozzle A preferred form of the invention and a modifi- I l is under. suflicient pressure, the bellows-24 and cation thereof are illustrated in the accompany- 25 will extend against the pressure of the spring ing drawing ,to which reference is made for a [9, and move the cup l5 away from the flange the drawing, duced into the inspirator I through the space Fig. 1 is a longitudinal sectional view through between the plate 3 andv the edge of the cup I5. I the device of my invention, parts being shown in The size of this space and the amount of air inelevation; and duced therethrough will vary with-the pressure Fig. 2 is a similar view of a modification. under which the fuel is supplied. This is deter- 45 An inspirator tube I having a Venturi throat 2 mined by the setting of the burner-control valve is adapted to deliver a combustible mixture of (not shown). On a decrease in the fuel pressure fuel and air to a heatexchange tube (not shown) resulting from partial closing of the control valve, for combustion therein. The end of the inspirafor example, the spring I8 will partially collapse v change tube. A flange plate 3 is secured to the cup. 15 to move toward the plate 3, thus restrictinspirator tube and has anopening in alinement ing the induction of air into the inspirator tube with the Venturi throat thereof. .An end plate 4 in accordance with the decreased fuel pressure.

is connected to the, flange-plate 3 by means of When the control valve is entirely closed, the 5 tie rods 5 and has a central opening through I edge of the cup l5 will engage the plate I and entirely out off flow of air through the inspirator and heat exchange tube which would, otherwise result from the natural draft due to the heated condition of the radiant tube.

Fig. 2 illustrates a modification in which several elements are the same as those of Fig. 1, or similar thereto, and these have been designated by the same reference numerals. The device of Fig. 2 includes a nozzle II' on which a disc 23' is mounted. A valve or closure member in the form of a cup I is movably mo ted on the nozzle H, a bellows 25' having one nd secured to the disc 23, and the other end to the rear wall of the cup l5. Another bellows 24' has one end attached to the rear wall of the cup l5 and the other end to the nozzle Ii. The bellows 24' merely provides a seal between the cup l5 and the nozzle II, and does not affect the expansion of the bellows 25 under the pressure of the fluid fuel. Ports 26 in the tube i i{ admit fuel from the nozzle-to the space within the bellows.

The operation of the device of Fig. 2 is similar to that of the apparatus shown inFig. 1, and no that my invention provides a simple and comparatively inexpensive device for automatically controlling the amount of air induced into a radiant tube for combustion therein, in accordance with the pressure under which the fuel is supplied and, therefore, the amount offuel available for combustion. The apparatus serves not only to proportion the amount of air induced to the amount of fuel available, so as to obtain efficient combustion at 'all times, but prevents the loss of heat .resulting from the induction of an excessive amount of cold air through the heated radiant tube. I

Although I have illustrated and described but one preferred embodiment of the invention and a modification thereof, it will be understood that changes in the exact details of construction herein disclosed may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a fuel feed and air cut-off apparatus for cooperation with an inspirator tube, the combination with a fuel injector nozzle spaced from one end of said tube whereby to discharge a fuel jet into the tube and induce'air into the latter from the space thereabout with the fuel, and a flange extending outwardly from one end of the tube, of a cup arranged coaxially of said nozzle with its rim adjacent said flange, an expansible chamber through which the nozzle extends, the end of the chamber adjacent the discharge end of the nozzle being secured to the latter, and means providing communication between the nozzle and the chamber, said cup being secured to said chamber at a point spaced from the fixed end of the latter for movement away from said flange when said chamber expands under the pressure of the fuel supplied to the nozzle.

2. A fuel feed and air cut-off device for cooperation with an inspirator tube comprising a fuel nozzle positioned to direct a jet into said tube, a flange extending outwardly from one end of the tube and having an opening therethrough in line with the tube, a cup disposed coaxially with the nozzle and extending back therealong from the discharge end of the nozzle, the rim of the cup being disposed adjacent said flange,

the fixed end thereof for movement away from said flange on expansion of said chamber.

JAMES C. WOODSON. 

